Abstract: The spine is a segmented axial structure comprised of alternating vertebral bodies (centra) and intervertebraldiscs(IVDs).Thecurrentmodelofspinepatterninghingesuponsegmentationoftheembryonic paraxial mesoderm (PM) and its subsequent re-segmentation and condensation around the notochord to producethecharacteristicalternatingpatternofcentraandIVDs.Whilemutationsinsegmentationgenes are known to cause spine defects, whether this machinery primarily affects patterning of the PM, the notochord,orbothremainsunknown.Thus,acompleteunderstandingofhowPM-derivedcellsmigrateto thenotochordtoproducesharpvertebralsegmentsseparatedbyregulargapsremainsunresolved. Using a zebrafish model, we will follow a comprehensive approach combining live imaging, transcriptomics and genetic manipulations to dissect the role of the notochord in the specification of vertebral segments and IVDs. Understanding the cellular and molecular mechanisms acting in the notochordduringspinesegmentationwillprovideamorecompleteunderstandingofvertebralpatterning.